Research suggests that happy delusions help when looking at your partner in a general sense (but be more realistic on the details).

If Cupid wanted to improve his game with science, he'd shoot first, then hand out rose-colored glasses with instructions attached:

To be worn when viewing your relationship and your partner's personality or body.

For best results, keep using well after "I do."

Remove carefully at your own risk.

Psychologists have long known that new love can be blind and new lovers delusional. Research has shown that newlyweds exaggerate their partner's good qualities, forget the bad ones, rate their own relationship with annoying superiority and so on.

But newer research tantalizingly suggests that this myopia is good for more than driving your single friends crazy. Some happy delusions may actually be better for the long-term health of a relationship than hewing to a sober and accurate view of your sweetheart.

Really? After all, common sense (and many a bitter veteran of marriage) would warn that just the opposite was true — that the higher you climb, the harder you fall after the honeymoon wears off. Wouldn't the starry-eyed, smugly optimistic folks be the most crushed when they wake up and realize that their Cinderella is really a chambermaid, their knight in shining armor actually a fat guy on a pony?

Not according to the evidence. Blinder is often better, it turns out. "Positive biases and happiness seem to push each other along," says Garth Fletcher, psychology professor at Victoria University of Wellington in New Zealand.

Researchers have noticed this "positive illusions" effect over and over again — with straight and gay couples, young and old, men and women, at the beginning of a relationship and decades along. It's there whether you're asking someone to evaluate a spouse's kindness and humor or his or her gorgeous face and hot body.

This can't all be explained by lucky people having partners who are actually sweeter, smarter or sexier than everyone else. Researchers adjust for that in their studies. What seems to be important is viewing one's partner and relationship as better than the evidence warrants.

Of course, seeing your partner as the cat's meow is part and parcel of falling in love, Fletcher says. But then, he adds, "When you've made the decision to commit, the positive biases really swing into action. Once the battle has begun, you have to be gung-ho. It can be fatal to do otherwise."

A study published in May in the journal Psychological Science helps show how rosy-tinted views affect a relationship down the line. Researchers followed 222 newlyweds for three years — time enough, science has shown, for the marital blahs to set in. Everyone in the study started out relatively happy and then their satisfaction declined — except in one group.

"People who were the most idealistic about their partner in the beginning showed no decline at all in satisfaction over the first three years of marriage," says study lead author Sandra Murray, psychology professor at the State University of New York at Buffalo.

And the effect was contagious, she says: If your partner was idealistic about you, then no matter what your beliefs, you ended up happier too.

The mechanisms still aren't entirely clear, adds Murray, who was one of the first researchers to identify the effect. Perhaps thinking your partner is the absolute shizzle makes you more likely to be committed and more constructive in dealing with him or her. Or it could be the other way around. "We've found that being idealized by your partner changes the way you feel about yourself," Murray says. In this way, positive illusions might be a self-fulfilling prophecy: We unconsciously live up to our partner's rosy view of us.

Relationship scientists are still refining the story. But they've found a few rules of thumb — and a few warnings.

• Positive illusions shouldn't be the equivalent of putting your fingers in your ears and singing, "Lalalalala, I don't hear you." Sunny optimism can be great as long as you and your partner communicate well, are committed to each other and have only mild problems, research has repeatedly shown.

"If the relationship has problems and you're willing to talk about it but your partner is just steadfastly stonewalling you — saying, 'Everything is great! Everything is wonderful!' — then that's not going to work at all," Fletcher says.

• You needn't lose your grasp on reality in order to harbor positive illusions. In fact, you probably shouldn't. Seeing your partner's relative strengths and weaknesses is almost as important as seeing them with a charitable eye. If your wife reasonably thinks she's a 5 out of 10 on ambition and a 7 on beauty, you're best off if you honestly and independently rate her as a 6 and 8, respectively. That way you're perceiving her fairly while still giving her an extra dollop of sunshine on top of her own estimations.